US9300217B2 - Electrolytic capacitor-less AC/DC converter and controlling method thereof - Google Patents

Electrolytic capacitor-less AC/DC converter and controlling method thereof Download PDF

Info

Publication number
US9300217B2
US9300217B2 US14/582,307 US201414582307A US9300217B2 US 9300217 B2 US9300217 B2 US 9300217B2 US 201414582307 A US201414582307 A US 201414582307A US 9300217 B2 US9300217 B2 US 9300217B2
Authority
US
United States
Prior art keywords
converter
terminal
voltage
capacitor
switching switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US14/582,307
Other versions
US20150180325A1 (en
Inventor
Tsorng-Juu Liang
Kuan-Wen Lee
Yi-Hsun Hsieh
Jiann-Fuh Chen
Yi-Chien Shen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Cheng Kung University NCKU
Original Assignee
National Cheng Kung University NCKU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Cheng Kung University NCKU filed Critical National Cheng Kung University NCKU
Assigned to NATIONAL CHENG KUNG UNIVERSITY reassignment NATIONAL CHENG KUNG UNIVERSITY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHEN, JIANN-FUH, LIANG, TSORNG-JUU, SHEN, YI-CHIEN, LEE, KUAN-WEN, HSIEH, YI-HSUN
Publication of US20150180325A1 publication Critical patent/US20150180325A1/en
Application granted granted Critical
Publication of US9300217B2 publication Critical patent/US9300217B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33538—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type
    • H02M3/33546—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only of the forward type with automatic control of the output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H02M1/15—Arrangements for reducing ripples from dc input or output using active elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4258—Arrangements for improving power factor of AC input using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage
    • H05B33/08—
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • the present invention relates to an electrolytic capacitor-less AC/DC converter and controlling method thereof, in particular to an electrolytic capacitor-less AC/DC converter including a current ripple eliminator and a voltage feedback control circuit.
  • the energy of the front stage of a conventional two-stage AC/DC converter can only be passed to the load through the rear stage.
  • the proposed AC/DC converter includes the current ripple eliminator to deal with the ripple power part only, and it thus has high efficiency.
  • an AC/DC converter generates an output voltage and comprises an isolated PFC converter, a current ripple eliminator electrically connected to the isolated PFC converter in parallel, a first capacitor electrically connected to the current ripple eliminator in parallel, and a voltage feedback control circuit including a second capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, and the second terminal generates a pure AC component of the voltage feedback signal, and a first resistor having a first and a second terminals, wherein the first terminal of the first resistor receives a DC bias, the second terminal of the first resistor is electrically connected to the second terminal of the second capacitor, and outputs a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
  • an AC/DC converter receives an AC input voltage signal, generates an output voltage, and comprises a non-isolated PFC converter, a current ripple eliminator electrically connected to the non-isolated PFC converter in parallel, a first capacitor electrically connected to the current ripple eliminator in parallel, and a voltage feedback control circuit including a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage, and a first resistor having a first and a second terminals, wherein the first terminal receives a DC bias, the second terminal is electrically connected to the first voltage divider to cause the second terminal to output a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
  • an AC/DC converter generates an output voltage and comprises a single-stage PFC converter, a current ripple eliminator electrically connected to the PFC converter in parallel, and a voltage feedback control circuit including a DC block capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, the second terminal generates a pure AC component of the voltage feedback signal, and a buffer resistor having a first and a second terminals, wherein the first terminal of the buffer resistor receives a DC bias, and the second terminal of the buffer resistor is electrically connected to the second terminal of the DC block capacitor to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
  • an AC/DC converter receives an AC input voltage signal, generates an output voltage, and comprises a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel, and a voltage feedback control circuit including a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage, and a buffer resistor having a first and a second terminals, wherein the first terminal receives a DC bias, and the second terminal is electrically connected to the first voltage divider to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
  • an AC/DC converter generates an output voltage and comprises a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, and when the input voltage is not larger than the first reference voltage, the energy storage capacitor releases the electric energy to the input voltage, and an operational amplifier operating the pure AC component and a second reference voltage to accurately determine when the energy storage capacitor should store or release the electric energy so as to minimize a ripple of an output power of the converter.
  • a controlling method for an AC/DC converter comprises providing a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the PFC circuit in parallel, and a voltage feedback control circuit electrically connected to the current ripple eliminator in parallel; outputting a control feedback signal from the voltage feedback control circuit to the current ripple eliminator when a peak value of an output voltage of the single-stage AC/DC PFC circuit is not less than a predetermined value such that a first output current caused by the peak value of the output voltage higher than the predetermined value flows into the current ripple eliminator to generate a stored electric energy so as to cause an output voltage of the converter to equal the predetermined value; and outputting the control feedback signal from the voltage feedback control circuit to the current ripple eliminator when the peak value of the output voltage of the single-stage AC/DC PFC circuit is less than the predetermined value such that the stored electric energy generates a second output current flowing out the current ripple eliminator to cause the output voltage of the converter to equal the predetermined value.
  • FIG. 1 is a schematic circuit diagram of an AC/DC converter according to the first preferred embodiment of the present invention.
  • FIG. 2 is a schematic circuit diagram of an AC/DC converter according to the second preferred embodiment of the present invention.
  • FIG. 3 is a schematic circuit diagram of an AC/DC converter according to the third preferred embodiment of the present invention.
  • FIG. 4 is a schematic circuit diagram of an AC/DC converter according to the fourth preferred embodiment of the present invention.
  • FIG. 5 is a schematic circuit diagram of an AC/DC converter according to the fifth preferred embodiment of the present invention.
  • FIG. 6 is a schematic circuit diagram of an AC/DC converter according to the sixth preferred embodiment of the present invention.
  • FIG. 1 shows a schematic diagram of an AC/DC converter 1 according to the first preferred embodiment of the present invention.
  • the AC/DC converter 1 includes an AC power source V ac , an electromagnetic interference (EMI) filter, a rectifier, a first single-stage AC/DC PFC converter 11 , a first current ripple eliminator 12 , an output capacitor C O , a first voltage divider 13 , an output inductor L O , an LED (it is a load), a sensing resistor R sense , a PFC controller, a first voltage feedback control circuit 14 , and a PWM controller 15 .
  • EMI electromagnetic interference
  • the AC/DC converter 1 receives a current I ac from the power source V ac , and has an input voltage V in , the rectifier has four rectifying diodes, and the first single-stage AC/DC PFC converter 11 is a flyback converter.
  • the flyback converter 11 has a first switch S 1 , a magnetizing inductor L m , and an isolation transformer (having a turns ratio of N p :N s ).
  • the first current ripple eliminator 12 has an input voltage P B , an output voltage P O , an inductor L B , a second switch S 2 , a third switch S 3 and a capacitor C B .
  • the first voltage divider 13 has two resistors, and outputs a voltage division feedback signal V fb , which has a DC component of V O _ avg .
  • the PWM controller 15 has an operational amplifier E/A and a comparator COMP, and the PWM controller 15 outputs a first gate control signal (from the output terminal of the COMP) transferring to the control terminal of the second switch S 2 , and a second gate control signal (from the output terminal of the COMP and then via a NOT gate to generate) transferring to the control terminal of the third switch S 3 to control the turn-on and the turn-off of the two switches S 2 and S 3 .
  • the first current ripple eliminator 12 with a simple voltage feedback control is used such that the first single-stage AC/DC PFC converter 11 can achieve the requirement of having smaller output voltage (current) ripple components without using an electrolytic capacitor.
  • the energy of the front stage of conventional two-stage AC/DC converter can only be passed to the load through the rear stage, and the proposed AC/DC converter (e.g., 1 ) includes the current ripple eliminator (e.g., 12 ) to deal with the ripple power part only, and thus to have high efficiency.
  • the current ripple eliminator 12 has a configuration of bi-directional boost converter, and achieves the stable output voltage (current) via adjusting the duty ratio or the duty cycle of the switch S 2 to control the magnitude of the input/output power so as to balance the output power.
  • the feedback of the output current component is required and a more complex extra circuit and with a higher cost is needed.
  • the proposed control method employs the voltage feedback signal originally included in the AC/DC PFC converter to control the current ripple eliminator, and the control scheme is simple.
  • the voltage division feedback of the output voltage is V fb , goes through a DC block capacitor to be filtered as a pure AC component, then adds a preset DC bias V Duty-offset to become a control feedback signal V si so as to provide to a common PWM controller to accomplish the control.
  • the AC component of V fb is used to control the magnitude of the duty ratio of the switches S 2 and S 3 to adjust the input and the output powers of the current ripple eliminator.
  • the V Duty-offset is used to set a reasonable DC bias to cause the V si to be compared with V ref of the PWM controller 15 to get the exact magnitude of the signal.
  • the V Duty-Offset can be generated via the voltage division of the built-in reference voltage level of the common PWM controller, there is no complex feedback circuit required, and V ref is the bias inside the comparator.
  • FIG. 2 shows a schematic diagram of an AC/DC converter 2 according to the second preferred embodiment of the present invention.
  • FIG. 2 is a preferred embodiment of electrolytic capacitor-less LED driver employing the proposed controlling method to the single-stage isolated AC/DC PFC converter 21 except for the flyback converter 11 .
  • FIG. 2 is a preferred embodiment adapting the first voltage feedback control circuit 14 and the first current ripple eliminator 12 above to the single-stage isolated AC/DC PFC converter 21 .
  • the applicable AC/DC PFC converters are not limited to the flyback converter 11 , or other single-stage isolated AC/DC PFC converter 21 , and a non-isolated PFC converter can be used also (described as follows).
  • the single-stage isolated AC/DC PFC converter 21 can be, for example, a forward converter.
  • FIG. 3 shows a schematic circuit diagram of an AC/DC converter 3 according to the third preferred embodiment of the present invention.
  • FIG. 3 is a configuration that the voltage feedback control circuit and the current ripple eliminator has been modulized, which includes the first voltage feedback control circuit 14 , the PWM controller 15 , and a second current ripple eliminator 31 (including an extra second voltage divider 311 ).
  • This module 31 is a simple two-terminal element, can be used to replace the electrolytic capacitor with a large capacitance at the rear side of a conventional AC/DC PFC converter, has the capability to be quickly replaced, and can raise the availability of the whole system.
  • FIG. 4 shows a schematic circuit diagram of an AC/DC converter 4 according to the fourth preferred embodiment of the present invention.
  • FIGS. 1 to 3 are embodiments of the present invention applied to AC/DC converters
  • FIG. 4 is an embodiment of the present invention applied to a single-stage non-isolated AC/DC PFC converter 41 .
  • the AC/DC converter 4 includes a single-stage non-isolated AC/DC PFC converter 41 and a second voltage feedback control circuit 42
  • the second voltage feedback control circuit 42 includes a third voltage divider 421 and a buffer resistor 422 . Because the input terminal and the output terminal therein have a common-ground relationship, the voltage feedback control signal can be obtained directly from the voltage division of the ripple voltage V ac of the input terminal, and the capacitor C Block in FIGS. 1 to 3 can be omitted.
  • FIG. 5 shows a schematic circuit diagram of an AC/DC converter 5 according to the fifth preferred embodiment of the present invention, wherein the difference between the AC/DC converter 5 and the AC/DC converter 1 of FIG. 1 is that the load of the AC/DC converter 5 is not limited to an LED.
  • this configuration 5 can be used to drive other kinds of loads ( 51 ), which require a stable output voltage (current), and can be adapted for use in the configurations of FIGS. 1 to 4 .
  • FIG. 6 shows a schematic circuit diagram of an AC/DC converter 6 according to the sixth preferred embodiment of the present invention.
  • the control approach employed in FIG. 6 does not receive the voltage feedback, and uses a fixed duty ratio to control switches S 2 and S 3 (because S 2 and S 3 are complementarily conducted to each other, only the duty ratio of S 2 is required to be controlled), can be viewed as an open-loop control, and has the advantage of having even more simplified configuration.
  • FIG. 6 and FIGS. 1 to 5 are that FIG. 6 does not have the first/the second voltage feedback control circuits 14 / 42 in FIGS. 1 to 5 because the fixed duty ratio is used.
  • the control approach employed in FIG. 6 requires a larger inductance of the boost inductor L B and a larger capacitance of the boost capacitor C B than those required by the control approaches used in FIGS. 1 to 5 .
  • the control approach in FIG. 6 is used:
  • i CB (t) is the current flowing from S 3 and going through the boost capacitor C B
  • v LB (t) is the cross voltage across the two terminals of the boost inductor L B
  • C B is the capacitance of the capacitor C B
  • L B is the inductance of the inductor L B
  • v CB (t) is the cross voltage across the two terminals of the boost capacitor C B
  • i LB (t) is the current flowing through L B
  • Vo is the output voltage of the AC/DC converter 6
  • V S2 (t) is the voltage at the electrical connection node between the inductor L B and the switch S 2
  • D S2 is the duty ratio of S 2
  • the optimized fixed duty ratio D S2,opt can be derived by assuming that the AC component i s (t) of the current flowing out the secondary side of the AC/DC PFC converter 11 is all flowing into the current ripple eliminator 12 (it is the current flowing through the inductor L B ).
  • I O is the amplitude of the output current of the AC/DC converter 6
  • ⁇ is the angle frequency of the input voltage
  • v CB (t) When formulas (4) and (3) are substituted into formula (2), v CB (t) can be expressed as:
  • An AC/DC converter generating an output voltage and comprising:
  • a voltage feedback control circuit including:
  • the isolated PFC converter is an isolated AC/DC PFC converter.
  • the PWM controller generates a first and a second control signals to control the first duty ratio of the second switching switch and the second duty ratio of the third switching switch
  • the isolated PFC converter has a first and a second output terminals
  • each of the second and the third switching switches has a first, a second, and a control terminals
  • the current ripple eliminator further includes a first inductor having a first and a second terminals, and a third capacitor having a first and a second terminals, the first terminal of the first inductor is electrically connected to the first output terminal of the isolated PFC converter, the second terminal of the first inductor is electrically connected to the first terminal of the second switching switch and the second terminal of the third switching switch, the first terminal of the first switching switch is electrically connected to the first terminal of the third capacitor, the second terminal of the third capacitor is electrically connected to the second terminal of the second switching switch and the second output terminal of the isolated PFC converter, the
  • each of the non-electrolytic capacitor, the second inductor, the load and the second resistor has a first and a second terminals, the first terminal of the second inductor is electrically connected to the first terminal of the non-electrolytic capacitor and the first output terminal of the isolated PFC converter, the second terminal of the second inductor is electrically connected to the first terminal of the load, the second terminal of the load is electrically connected to the first terminal of the second resistor and the PFC controller, and the second terminal of the second resistor is electrically connected to the second output terminal of the isolated PFC converter and a common ground.
  • An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
  • a voltage feedback control circuit including:
  • the AC/DC converter according to Embodiment 6 further comprising a first and a second input terminals and a first and a second output terminals, wherein the non-isolated PFC converter is a non-isolated AC/DC PFC converter, and the second input terminal and the second output terminal of the AC/DC converter have a common ground.
  • the non-isolated AC/DC PFC converter is one selected from a group consisting of a buck converter, a boost converter, a buck-boost converter, a Cuk converter, a Sepic converter, and a Zeta converter.
  • An AC/DC converter generating an output voltage and comprising:
  • a voltage feedback control circuit including:
  • An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
  • a voltage feedback control circuit including:
  • An AC/DC converter generating an output voltage and comprising:
  • a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, and when the input voltage is not larger than the first reference voltage, the energy storage capacitor releases the electric energy to the input voltage;
  • an operational amplifier operating the pure AC component and a second reference voltage to accurately determine when the energy storage capacitor should store or release the electric energy so as to minimize a ripple of an output power of the converter.
  • An AC/DC converter receiving an AC input voltage and comprising:
  • a current ripple eliminator including:
  • a controlling method for an AC/DC converter comprising:
  • a controlling method for an AC/DC converter comprising:
  • a current ripple eliminator having a first inductor and a switching circuit electrically connected to the first inductor in series, wherein the switching circuit has a first capacitor, a first switching switch and a second switching switch, the second switching switch is electrically connected to the first capacitor in series, and the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel;
  • the present invention discloses an AC/DC converter including an output capacitor with a small capacitance and a long lifespan, and using a current ripple eliminator with a simple voltage feedback control such that a single-stage AC/DC PFC converter included in the proposed converter can achieve the requirement of having a smaller output voltage (current) ripple components without using an electrolytic capacitor.
  • the energy of the front stage of conventional two-stage AC/DC converter can only be passed to the load through the rear stage.
  • the proposed AC/DC converter includes the current ripple eliminator to deal with the ripple power part only, and thus has high efficiency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

An AC/DC converter is disclosed. The proposed AC/DC converter generates an output voltage and includes a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, otherwise, the energy storage capacitor releases the electric energy to the input voltage, and an operational amplifier operating the AC component and a second reference voltage to determine when the storage capacitor should store or release the electric energy to minimize a ripple of an output power thereof.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefits of Taiwan Patent Application Number 102148300 filed on Dec. 25, 2013, at the Taiwan Intellectual Property Office, the disclosures of which are incorporated herein in their entirety by reference.
FIELD OF THE INVENTION
The present invention relates to an electrolytic capacitor-less AC/DC converter and controlling method thereof, in particular to an electrolytic capacitor-less AC/DC converter including a current ripple eliminator and a voltage feedback control circuit.
BACKGROUND OF THE INVENTION
The conventional two-stage light emitting diode (LED) driver and one-stage light emitting diode (LED) driver both include electrolytic capacitors having large capacitance to act as an energy storage element so as to provide stable output power. The larger the capacitance employed, the smaller the low frequency (120 Hz) ripple components of the output voltage (current) are, and vise versa. If electrolytic capacitors having large capacitance are not used, then the output voltage (current) fluctuates, which results in a blinking light phenomenon.
Thus, how to avoid the drawbacks of causing fluctuation of the output voltage (current) and the resulting blinking light phenomenon when electrolytic capacitors with large capacitance are not used is worthy of further research and improvement.
Keeping the drawbacks of the prior art in mind, and through the use of robust and persistent experiments and research, the applicant has finally conceived of an electrolytic capacitor-less AC/DC converter and a controlling method thereof.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide an AC/DC converter including an output capacitor with a small capacitance and a long lifespan, and using a current ripple eliminator with a simple voltage feedback control such that a single-stage AC/DC PFC converter included in the proposed converter can achieve the requirement of having smaller output voltage (current) ripple components without using an electrolytic capacitor. The energy of the front stage of a conventional two-stage AC/DC converter can only be passed to the load through the rear stage. But, the proposed AC/DC converter includes the current ripple eliminator to deal with the ripple power part only, and it thus has high efficiency.
In accordance with the first aspect of the present invention, an AC/DC converter generates an output voltage and comprises an isolated PFC converter, a current ripple eliminator electrically connected to the isolated PFC converter in parallel, a first capacitor electrically connected to the current ripple eliminator in parallel, and a voltage feedback control circuit including a second capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, and the second terminal generates a pure AC component of the voltage feedback signal, and a first resistor having a first and a second terminals, wherein the first terminal of the first resistor receives a DC bias, the second terminal of the first resistor is electrically connected to the second terminal of the second capacitor, and outputs a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
In accordance with the second aspect of the present invention, an AC/DC converter receives an AC input voltage signal, generates an output voltage, and comprises a non-isolated PFC converter, a current ripple eliminator electrically connected to the non-isolated PFC converter in parallel, a first capacitor electrically connected to the current ripple eliminator in parallel, and a voltage feedback control circuit including a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage, and a first resistor having a first and a second terminals, wherein the first terminal receives a DC bias, the second terminal is electrically connected to the first voltage divider to cause the second terminal to output a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
In accordance with the third aspect of the present invention, an AC/DC converter generates an output voltage and comprises a single-stage PFC converter, a current ripple eliminator electrically connected to the PFC converter in parallel, and a voltage feedback control circuit including a DC block capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, the second terminal generates a pure AC component of the voltage feedback signal, and a buffer resistor having a first and a second terminals, wherein the first terminal of the buffer resistor receives a DC bias, and the second terminal of the buffer resistor is electrically connected to the second terminal of the DC block capacitor to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
In accordance with the fourth aspect of the present invention, an AC/DC converter receives an AC input voltage signal, generates an output voltage, and comprises a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel, and a voltage feedback control circuit including a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage, and a buffer resistor having a first and a second terminals, wherein the first terminal receives a DC bias, and the second terminal is electrically connected to the first voltage divider to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
In accordance with the fifth aspect of the present invention, an AC/DC converter generates an output voltage and comprises a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, and when the input voltage is not larger than the first reference voltage, the energy storage capacitor releases the electric energy to the input voltage, and an operational amplifier operating the pure AC component and a second reference voltage to accurately determine when the energy storage capacitor should store or release the electric energy so as to minimize a ripple of an output power of the converter.
In accordance with the sixth aspect of the present invention, an AC/DC converter receives an AC input voltage and comprises a current ripple eliminator including a first inductor, and a switching circuit electrically connected to the first inductor in series and having a first capacitor, a first switching switch and a second switching switch, wherein the second switching switch is electrically connected to the first capacitor in series, the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel, a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of the AC input voltage, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
In accordance with the seventh aspect of the present invention, a controlling method for an AC/DC converter comprises providing a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the PFC circuit in parallel, and a voltage feedback control circuit electrically connected to the current ripple eliminator in parallel; outputting a control feedback signal from the voltage feedback control circuit to the current ripple eliminator when a peak value of an output voltage of the single-stage AC/DC PFC circuit is not less than a predetermined value such that a first output current caused by the peak value of the output voltage higher than the predetermined value flows into the current ripple eliminator to generate a stored electric energy so as to cause an output voltage of the converter to equal the predetermined value; and outputting the control feedback signal from the voltage feedback control circuit to the current ripple eliminator when the peak value of the output voltage of the single-stage AC/DC PFC circuit is less than the predetermined value such that the stored electric energy generates a second output current flowing out the current ripple eliminator to cause the output voltage of the converter to equal the predetermined value.
In accordance with the eighth aspect of the present invention, a controlling method for an AC/DC converter comprises providing a current ripple eliminator having a first inductor and a switching circuit electrically connected to the first inductor in series, wherein the switching circuit has a first capacitor, a first switching switch and a second switching switch, the second switching switch is electrically connected to the first capacitor in series, and the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel; and causing a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of an AC input voltage of the converter, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objectives, advantages and the efficacy of the present invention will be described in detail below taken from the preferred embodiments with reference to the accompanying drawings, in which:
FIG. 1 is a schematic circuit diagram of an AC/DC converter according to the first preferred embodiment of the present invention.
FIG. 2 is a schematic circuit diagram of an AC/DC converter according to the second preferred embodiment of the present invention.
FIG. 3 is a schematic circuit diagram of an AC/DC converter according to the third preferred embodiment of the present invention.
FIG. 4 is a schematic circuit diagram of an AC/DC converter according to the fourth preferred embodiment of the present invention.
FIG. 5 is a schematic circuit diagram of an AC/DC converter according to the fifth preferred embodiment of the present invention.
FIG. 6 is a schematic circuit diagram of an AC/DC converter according to the sixth preferred embodiment of the present invention.
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purposes of illustration and description only; they are not intended to be exhaustive or to be limited to the precise form disclosed.
FIG. 1 shows a schematic diagram of an AC/DC converter 1 according to the first preferred embodiment of the present invention. In FIG. 1, the AC/DC converter 1 includes an AC power source Vac, an electromagnetic interference (EMI) filter, a rectifier, a first single-stage AC/DC PFC converter 11, a first current ripple eliminator 12, an output capacitor CO, a first voltage divider 13, an output inductor LO, an LED (it is a load), a sensing resistor Rsense, a PFC controller, a first voltage feedback control circuit 14, and a PWM controller 15. As shown in FIG. 1, the AC/DC converter 1 receives a current Iac from the power source Vac, and has an input voltage Vin, the rectifier has four rectifying diodes, and the first single-stage AC/DC PFC converter 11 is a flyback converter. The flyback converter 11 has a first switch S1, a magnetizing inductor Lm, and an isolation transformer (having a turns ratio of Np:Ns). The first current ripple eliminator 12 has an input voltage PB, an output voltage PO, an inductor LB, a second switch S2, a third switch S3 and a capacitor CB. The first voltage divider 13 has two resistors, and outputs a voltage division feedback signal Vfb, which has a DC component of VO _ avg. The PWM controller 15 has an operational amplifier E/A and a comparator COMP, and the PWM controller 15 outputs a first gate control signal (from the output terminal of the COMP) transferring to the control terminal of the second switch S2, and a second gate control signal (from the output terminal of the COMP and then via a NOT gate to generate) transferring to the control terminal of the third switch S3 to control the turn-on and the turn-off of the two switches S2 and S3. The capacitor CO in FIG. 1 employs a capacitor having a small capacitance and a long lifespan to replace the electrolytic capacitor, and a first current ripple eliminator 12 with a simple voltage feedback control is used such that the first single-stage AC/DC PFC converter 11 can achieve the requirement of having smaller output voltage (current) ripple components without using an electrolytic capacitor. The energy of the front stage of conventional two-stage AC/DC converter can only be passed to the load through the rear stage, and the proposed AC/DC converter (e.g., 1) includes the current ripple eliminator (e.g., 12) to deal with the ripple power part only, and thus to have high efficiency.
In FIG. 1, the current ripple eliminator 12 has a configuration of bi-directional boost converter, and achieves the stable output voltage (current) via adjusting the duty ratio or the duty cycle of the switch S2 to control the magnitude of the input/output power so as to balance the output power. In the conventional approach to control the current ripple eliminator, the feedback of the output current component is required and a more complex extra circuit and with a higher cost is needed. In the present invention, the proposed control method employs the voltage feedback signal originally included in the AC/DC PFC converter to control the current ripple eliminator, and the control scheme is simple. The voltage division feedback of the output voltage is Vfb, goes through a DC block capacitor to be filtered as a pure AC component, then adds a preset DC bias VDuty-offset to become a control feedback signal Vsi so as to provide to a common PWM controller to accomplish the control. The AC component of Vfb is used to control the magnitude of the duty ratio of the switches S2 and S3 to adjust the input and the output powers of the current ripple eliminator. The VDuty-offset is used to set a reasonable DC bias to cause the Vsi to be compared with Vref of the PWM controller 15 to get the exact magnitude of the signal. The VDuty-Offset can be generated via the voltage division of the built-in reference voltage level of the common PWM controller, there is no complex feedback circuit required, and Vref is the bias inside the comparator.
FIG. 2 shows a schematic diagram of an AC/DC converter 2 according to the second preferred embodiment of the present invention. FIG. 2 is a preferred embodiment of electrolytic capacitor-less LED driver employing the proposed controlling method to the single-stage isolated AC/DC PFC converter 21 except for the flyback converter 11. FIG. 2 is a preferred embodiment adapting the first voltage feedback control circuit 14 and the first current ripple eliminator 12 above to the single-stage isolated AC/DC PFC converter 21. Certainly, the applicable AC/DC PFC converters are not limited to the flyback converter 11, or other single-stage isolated AC/DC PFC converter 21, and a non-isolated PFC converter can be used also (described as follows). The single-stage isolated AC/DC PFC converter 21 can be, for example, a forward converter.
FIG. 3 shows a schematic circuit diagram of an AC/DC converter 3 according to the third preferred embodiment of the present invention. FIG. 3 is a configuration that the voltage feedback control circuit and the current ripple eliminator has been modulized, which includes the first voltage feedback control circuit 14, the PWM controller 15, and a second current ripple eliminator 31 (including an extra second voltage divider 311). This module 31 is a simple two-terminal element, can be used to replace the electrolytic capacitor with a large capacitance at the rear side of a conventional AC/DC PFC converter, has the capability to be quickly replaced, and can raise the availability of the whole system.
FIG. 4 shows a schematic circuit diagram of an AC/DC converter 4 according to the fourth preferred embodiment of the present invention. FIGS. 1 to 3 are embodiments of the present invention applied to AC/DC converters, and FIG. 4 is an embodiment of the present invention applied to a single-stage non-isolated AC/DC PFC converter 41. As shown in FIG. 4, the differences between the AC/DC converter 4 and the AC/ DC converters 1, 2 and 3 above are that the AC/DC converter 4 includes a single-stage non-isolated AC/DC PFC converter 41 and a second voltage feedback control circuit 42, and the second voltage feedback control circuit 42 includes a third voltage divider 421 and a buffer resistor 422. Because the input terminal and the output terminal therein have a common-ground relationship, the voltage feedback control signal can be obtained directly from the voltage division of the ripple voltage Vac of the input terminal, and the capacitor CBlock in FIGS. 1 to 3 can be omitted.
The LED load in FIGS. 1 to 4 can be change to a non-LED load. FIG. 5 shows a schematic circuit diagram of an AC/DC converter 5 according to the fifth preferred embodiment of the present invention, wherein the difference between the AC/DC converter 5 and the AC/DC converter 1 of FIG. 1 is that the load of the AC/DC converter 5 is not limited to an LED. Thus, this configuration 5 can be used to drive other kinds of loads (51), which require a stable output voltage (current), and can be adapted for use in the configurations of FIGS. 1 to 4.
FIG. 6 shows a schematic circuit diagram of an AC/DC converter 6 according to the sixth preferred embodiment of the present invention. The control approach employed in FIG. 6 does not receive the voltage feedback, and uses a fixed duty ratio to control switches S2 and S3 (because S2 and S3 are complementarily conducted to each other, only the duty ratio of S2 is required to be controlled), can be viewed as an open-loop control, and has the advantage of having even more simplified configuration. The differences between FIG. 6 and FIGS. 1 to 5 are that FIG. 6 does not have the first/the second voltage feedback control circuits 14/42 in FIGS. 1 to 5 because the fixed duty ratio is used. The control approach employed in FIG. 6 requires a larger inductance of the boost inductor LB and a larger capacitance of the boost capacitor CB than those required by the control approaches used in FIGS. 1 to 5. When the control approach in FIG. 6 is used:
i CB ⁡ ( t ) = C B · ⅆ v CB ⁡ ( t ) ⅆ t ⁢ ⁢ and ( 1 ) v LB ⁡ ( t ) = L B · ⅆ i CB ⁡ ( t ) ⅆ t , ( 2 )
where iCB(t) is the current flowing from S3 and going through the boost capacitor CB, vLB(t) is the cross voltage across the two terminals of the boost inductor LB, CB is the capacitance of the capacitor CB, LB is the inductance of the inductor LB, vCB(t) is the cross voltage across the two terminals of the boost capacitor CB, iLB(t) is the current flowing through LB. And, vLB(t) can be also expressed as:
v LB(t)=Vo−v S2(t)=Vo−(1−D S2)v CB(t)  (3)
where Vo is the output voltage of the AC/DC converter 6, VS2(t) is the voltage at the electrical connection node between the inductor LB and the switch S2, DS2 is the duty ratio of S2, the optimized fixed duty ratio DS2,opt can be derived by assuming that the AC component is(t) of the current flowing out the secondary side of the AC/DC PFC converter 11 is all flowing into the current ripple eliminator 12 (it is the current flowing through the inductor LB).
i LB(t)=i s(t)=I O sin(2ωt)  (4),
where IO is the amplitude of the output current of the AC/DC converter 6, ω is the angle frequency of the input voltage.
And, iCB(t) can also be expressed as:
i CB(t)=(1−D S2,opt)·I O sin(2ωt)  (5).
When formulas (4) and (3) are substituted into formula (2), vCB(t) can be expressed as:
V O - ( 1 - D S ⁢ ⁢ 2 , opt ) ⁢ v CB ⁡ ( t ) = L B · [ 2 ⁢ ⁢ ω ⁢ ⁢ I O ⁢ cos ⁡ ( 2 ⁢ ⁢ ω ⁢ ⁢ t ) ] -> v CB ⁡ ( t ) = V O - 2 ⁢ ⁢ ω ⁢ ⁢ L B ⁢ I O ⁢ cos ⁡ ( 2 ⁢ ⁢ ω ⁢ ⁢ t ) ( 1 - D S ⁢ ⁢ 2 , opt ) . ( 6 )
When formulas (5) and (6) are substituted into formula (1), we get:
( 1 - D S ⁢ ⁢ 2 , opt ) · I O ⁢ sin ⁡ ( 2 ⁢ ⁢ ω ⁢ ⁢ t ) = C B · 1 ( 1 - D S ⁢ ⁢ 2 , opt ) · [ 4 ⁢ ⁢ ω 2 ⁢ L B ⁢ I O ⁢ sin ⁡ ( 2 ⁢ ⁢ ω ⁢ ⁢ t ) ] ( 7 )
After rearranging formula (7), we get:
(1−D S2,opt)2=4ω2 ·L B ·C B  (8).
And we know: D S2,opt=1−2ω(L B ·C B)(1/2)  (9),
where ω=2πf, f is a working frequency of the input voltage Vac.
Embodiments
1. An AC/DC converter generating an output voltage and comprising:
an isolated PFC converter;
a current ripple eliminator electrically connected to the isolated PFC converter in parallel;
a first capacitor electrically connected to the current ripple eliminator in parallel; and
a voltage feedback control circuit including:
    • a second capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, and the second terminal generates a pure AC component of the voltage feedback signal; and
    • a first resistor having a first and a second terminals, wherein the first terminal of the first resistor receives a DC bias, the second terminal of the first resistor is electrically connected to the second terminal of the second capacitor, and outputs a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
2. The AC/DC converter according to Embodiment 1, further comprising a voltage divider, a power factor correction (PFC) controller and a pulse width modulation (PWM) controller, wherein the DC bias is generated by a voltage division of a built-in reference voltage level of the PWM controller, the isolated PFC converter has a first switching switch, the first capacitor is a non-electrolytic capacitor, the second capacitor is a DC block capacitor, the current ripple eliminator has a second switching switch and a third switching switch, the voltage divider is electrically connected to the non-electrolytic capacitor in parallel, and outputs the voltage feedback signal, the PFC controller receives the voltage feedback signal to be used to control magnitudes of a first duty cycle of the second switching switch, and a second duty cycle of the third switching switch so as to respectively control the input power and the output power, and the isolated PFC converter is an isolated AC/DC PFC converter.
3. The AC/DC converter according to Embodiment 1 or 2, wherein the isolated AC/DC PFC converter is one of a flyback converter and a forward converter.
4. The AC/DC converter according to any one of the above-mentioned Embodiments, wherein the PWM controller generates a first and a second control signals to control the first duty ratio of the second switching switch and the second duty ratio of the third switching switch, the isolated PFC converter has a first and a second output terminals, each of the second and the third switching switches has a first, a second, and a control terminals, the current ripple eliminator further includes a first inductor having a first and a second terminals, and a third capacitor having a first and a second terminals, the first terminal of the first inductor is electrically connected to the first output terminal of the isolated PFC converter, the second terminal of the first inductor is electrically connected to the first terminal of the second switching switch and the second terminal of the third switching switch, the first terminal of the first switching switch is electrically connected to the first terminal of the third capacitor, the second terminal of the third capacitor is electrically connected to the second terminal of the second switching switch and the second output terminal of the isolated PFC converter, the control terminal of the second switching switch receives the first control signal, and the control terminal of the third switching switch receives the second control signal.
5. The AC/DC converter according to any one of the above-mentioned Embodiments, further comprising a second inductor, a load and a second resistor, wherein each of the non-electrolytic capacitor, the second inductor, the load and the second resistor has a first and a second terminals, the first terminal of the second inductor is electrically connected to the first terminal of the non-electrolytic capacitor and the first output terminal of the isolated PFC converter, the second terminal of the second inductor is electrically connected to the first terminal of the load, the second terminal of the load is electrically connected to the first terminal of the second resistor and the PFC controller, and the second terminal of the second resistor is electrically connected to the second output terminal of the isolated PFC converter and a common ground.
6. An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
a non-isolated PFC converter;
a current ripple eliminator electrically connected to the non-isolated PFC converter in parallel;
a first capacitor electrically connected to the current ripple eliminator in parallel; and
a voltage feedback control circuit including:
    • a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage; and a first resistor having a first and a second terminals, wherein the
    • first terminal receives a DC bias, the second terminal is electrically connected to the first voltage divider to cause the second terminal to output a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
7. The AC/DC converter according to Embodiment 6, further comprising a first and a second input terminals and a first and a second output terminals, wherein the non-isolated PFC converter is a non-isolated AC/DC PFC converter, and the second input terminal and the second output terminal of the AC/DC converter have a common ground.
8. The AC/DC converter according to Embodiment 6 or 7, wherein the non-isolated AC/DC PFC converter is one selected from a group consisting of a buck converter, a boost converter, a buck-boost converter, a Cuk converter, a Sepic converter, and a Zeta converter.
9. An AC/DC converter generating an output voltage and comprising:
a single-stage PFC converter;
a current ripple eliminator electrically connected to the PFC converter in parallel; and
a voltage feedback control circuit including:
    • a DC block capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, the second terminal generates a pure AC component of the voltage feedback signal; and
    • a buffer resistor having a first and a second terminals, wherein the first terminal of the buffer resistor receives a DC bias, and the second terminal of the buffer resistor is electrically connected to the second terminal of the DC block capacitor to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
10. The AC/DC converter according to Embodiment 9, wherein the single-stage PFC converter is a single-stage AC/DC PFC converter.
11. An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
a single-stage AC/DC PFC circuit;
a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel; and
a voltage feedback control circuit including:
    • a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage; and
    • a buffer resistor having a first and a second terminals, wherein the first terminal receives a DC bias, and the second terminal is electrically connected to the first voltage divider to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
12. An AC/DC converter generating an output voltage and comprising:
a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, and when the input voltage is not larger than the first reference voltage, the energy storage capacitor releases the electric energy to the input voltage; and
an operational amplifier operating the pure AC component and a second reference voltage to accurately determine when the energy storage capacitor should store or release the electric energy so as to minimize a ripple of an output power of the converter.
13. The AC/DC converter according to Embodiment 12, further comprising a voltage divider and a non-electrolytic capacitor, wherein the output terminal includes a first terminal and a second terminal, the voltage divider and the non-electrolytic capacitor are electrically connected to the first and the second terminals in parallel, and the voltage divider generates the voltage feedback signal.
14. An AC/DC converter receiving an AC input voltage and comprising:
a current ripple eliminator including:
    • a first inductor; and
    • a switching circuit electrically connected to the first inductor in series and having a first capacitor, a first switching switch and a second switching switch, wherein the second switching switch is electrically connected to the first capacitor in series, the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel, a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of the AC input voltage, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
15. The AC/DC converter according to Embodiment 14, further comprising a single-stage AC/DC PFC circuit and a non-electrolytic capacitor, wherein each of the current ripple eliminator, the first inductor, the first capacitor, the first switching switch and the second switching switch has a first and a second terminals, the first terminal of the first inductor is electrically connected to the first terminal of the current ripple eliminator, the second terminal of the first inductor is electrically connected to the first terminal of the first switching switch and the second terminal of the second switching switch, the first terminal of the second switching switch is electrically connected to the first terminal of the first capacitor, the second terminal of the first capacitor is electrically connected to the second terminal of the first switching switch and the second terminal of the current ripple eliminator, the single-stage AC/DC PFC circuit and the non-electrolytic capacitor are electrically connected to the first and the second terminals of the current ripple eliminator in parallel, the duty ratio is used to control a turn-on and a turn-off of the first switching switch, and the first switching switch and the second switching switch are complementarily turned on and turned off to each other in the same period, wherein in the same period, when the first switching switch is turned on, the second switching switch is turned off, and when the first switching switch is turned off, the second switching switch is turned on, a minimum cross voltage of the first capacitor is larger than an input voltage of the current ripple eliminator, and a maximum cross voltage of the first capacitor is less than a rated voltage of the first capacitor.
16. A controlling method for an AC/DC converter, comprising:
providing a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel, and a voltage feedback control circuit electrically connected to the current ripple eliminator in parallel;
outputting a control feedback signal from the voltage feedback control circuit to the current ripple eliminator when a peak value of an output voltage of the single-stage AC/DC PFC circuit is not less than a predetermined value such that a first output current caused by the peak value of the output voltage higher than the predetermined value flows into the current ripple eliminator to generate a stored electric energy so as to cause an output voltage of the converter to equal the predetermined value; and
outputting the control feedback signal from the voltage feedback control circuit to the current ripple eliminator when the peak value of the output voltage of the single-stage AC/DC PFC circuit is less than the predetermined value such that the stored electric energy generates a second output current flowing out the current ripple eliminator to cause the output voltage of the converter to equal the predetermined value.
17. The controlling method according to Embodiment 16, wherein the AC/DC converter is the AC/DC converter as disclosed in one of Embodiment 5 and Embodiment 7.
18. A controlling method for an AC/DC converter, comprising:
providing a current ripple eliminator having a first inductor and a switching circuit electrically connected to the first inductor in series, wherein the switching circuit has a first capacitor, a first switching switch and a second switching switch, the second switching switch is electrically connected to the first capacitor in series, and the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel; and
causing a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of an AC input voltage of the converter, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
According to the descriptions above, the present invention discloses an AC/DC converter including an output capacitor with a small capacitance and a long lifespan, and using a current ripple eliminator with a simple voltage feedback control such that a single-stage AC/DC PFC converter included in the proposed converter can achieve the requirement of having a smaller output voltage (current) ripple components without using an electrolytic capacitor. The energy of the front stage of conventional two-stage AC/DC converter can only be passed to the load through the rear stage. But, the proposed AC/DC converter includes the current ripple eliminator to deal with the ripple power part only, and thus has high efficiency.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. Therefore, it is intended to cover various modifications and similar configuration included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

Claims (18)

What is claimed is:
1. An AC/DC converter generating an output voltage and comprising:
an isolated PFC converter;
a current ripple eliminator electrically connected to the isolated PFC converter in parallel;
a first capacitor electrically connected to the current ripple eliminator in parallel; and
a voltage feedback control circuit including:
a second capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, and the second terminal generates a pure AC component of the voltage feedback signal; and
a first resistor having a first and a second terminals, wherein the first terminal of the first resistor receives a DC bias, the second terminal of the first resistor is electrically connected to the second terminal of the second capacitor, and outputs a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
2. The AC/DC converter according to claim 1, further comprising a voltage divider, a power factor correction (PFC) controller and a pulse width modulation (PWM) controller, wherein the DC bias is generated by a voltage division of a built-in reference voltage level of the PWM controller, the isolated PFC converter has a first switching switch, the first capacitor is a non-electrolytic capacitor, the second capacitor is a DC block capacitor, the current ripple eliminator has a second switching switch and a third switching switch, the voltage divider is electrically connected to the non-electrolytic capacitor in parallel, and outputs the voltage feedback signal, the PFC controller receives the voltage feedback signal to be used to control magnitudes of a first duty cycle of the second switching switch, and a second duty cycle of the third switching switch so as to respectively control the input power and the output power, and the isolated PFC converter is an isolated AC/DC PFC converter.
3. The AC/DC converter according to claim 2, wherein the isolated AC/DC PFC converter is one of a flyback converter and a forward converter.
4. The AC/DC converter according to claim 2, wherein the PWM controller generates a first and a second control signals to control the first duty ratio of the second switching switch and the second duty ratio of the third switching switch, the isolated PFC converter has a first and a second output terminals, each of the second and the third switching switches has a first, a second, and a control terminals, the current ripple eliminator further includes a first inductor having a first and a second terminals, and a third capacitor having a first and a second terminals, the first terminal of the first inductor is electrically connected to the first output terminal of the isolated PFC converter, the second terminal of the first inductor is electrically connected to the first terminal of the second switching switch and the second terminal of the third switching switch, the first terminal of the first switching switch is electrically connected to the first terminal of the third capacitor, the second terminal of the third capacitor is electrically connected to the second terminal of the second switching switch and the second output terminal of the isolated PFC converter, the control terminal of the second switching switch receives the first control signal, and the control terminal of the third switching switch receives the second control signal.
5. The AC/DC converter according to claim 4, further comprising a second inductor, a load and a second resistor, wherein each of the non-electrolytic capacitor, the second inductor, the load and the second resistor has a first and a second terminals, the first terminal of the second inductor is electrically connected to the first terminal of the non-electrolytic capacitor and the first output terminal of the isolated PFC converter, the second terminal of the second inductor is electrically connected to the first terminal of the load, the second terminal of the load is electrically connected to the first terminal of the second resistor and the PFC controller, and the second terminal of the second resistor is electrically connected to the second output terminal of the isolated PFC converter and a common ground.
6. An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
a non-isolated PFC converter;
a current ripple eliminator electrically connected to the non-isolated PFC converter in parallel;
a first capacitor electrically connected to the current ripple eliminator in parallel; and
a voltage feedback control circuit including:
a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage; and
a first resistor having a first and a second terminals, wherein the first terminal receives a DC bias, the second terminal is electrically connected to the first voltage divider to cause the second terminal to output a control feedback signal including the DC bias and the pure AC component, and the control feedback signal is used to control an input power and an output power of the current ripple eliminator so as to minimize a ripple of an output power of the AC/DC converter.
7. The AC/DC converter according to claim 6, further comprising a first and a second input terminals and a first and a second output terminals, wherein the non-isolated PFC converter is a non-isolated AC/DC PFC converter, and the second input terminal and the second output terminal of the AC/DC converter have a common ground.
8. The AC/DC converter according to claim 7, wherein the non-isolated AC/DC PFC converter is one selected from a group consisting of a buck converter, a boost converter, a buck-boost converter, a Cuk converter, a Sepic converter, and a Zeta converter.
9. An AC/DC converter generating an output voltage and comprising:
a single-stage PFC converter;
a current ripple eliminator electrically connected to the PFC converter in parallel; and
a voltage feedback control circuit including:
a DC block capacitor having a first and a second terminals, wherein the first terminal receives a voltage feedback signal based on the output voltage, the second terminal generates a pure AC component of the voltage feedback signal; and
a buffer resistor having a first and a second terminals, wherein the first terminal of the buffer resistor receives a DC bias, and the second terminal of the buffer resistor is electrically connected to the second terminal of the DC block capacitor to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
10. The AC/DC converter according to claim 9, wherein the single-stage PFC converter is a single-stage AC/DC PFC converter.
11. An AC/DC converter receiving an AC input voltage signal, generating an output voltage, and comprising:
a single-stage AC/DC PFC circuit;
a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel; and
a voltage feedback control circuit including:
a first voltage divider receiving the AC input voltage signal to generate a pure AC component of a voltage feedback signal based on the output voltage; and
a buffer resistor having a first and a second terminals, wherein the first terminal receives a DC bias, and the second terminal is electrically connected to the first voltage divider to cause the voltage feedback control circuit to output a control feedback signal including the pure AC component and the DC bias so as to minimize a ripple of an output power of the AC/DC converter.
12. An AC/DC converter generating an output voltage and comprising:
a current ripple eliminator having an input terminal, an energy storage capacitor and an output terminal, wherein the input terminal has an input voltage, the output terminal generates a pure AC component of a voltage feedback signal based on the output voltage, when the input voltage is larger than a first reference voltage, the energy storage capacitor stores a difference between the input voltage and the first reference voltage as an electric energy, and when the input voltage is not larger than the first reference voltage, the energy storage capacitor releases the electric energy to the input voltage; and
an operational amplifier operating the pure AC component and a second reference voltage to accurately determine when the energy storage capacitor should store or release the electric energy so as to minimize a ripple of an output power of the converter.
13. The AC/DC converter according to claim 12, further comprising a voltage divider and a non-electrolytic capacitor, wherein the output terminal includes a first terminal and a second terminal, the voltage divider and the non-electrolytic capacitor are electrically connected to the first and the second terminals in parallel, and the voltage divider generates the voltage feedback signal.
14. An AC/DC converter receiving an AC input voltage and comprising:
a current ripple eliminator including:
a first inductor; and
a switching circuit electrically connected to the first inductor in series and having a first capacitor, a first switching switch and a second switching switch, wherein the second switching switch is electrically connected to the first capacitor in series, the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel, a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of the AC input voltage, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
15. The AC/DC converter according to claim 14, further comprising a single-stage AC/DC PFC circuit and a non-electrolytic capacitor, wherein each of the current ripple eliminator, the first inductor, the first capacitor, the first switching switch and the second switching switch has a first and a second terminals, the first terminal of the first inductor is electrically connected to the first terminal of the current ripple eliminator, the second terminal of the first inductor is electrically connected to the first terminal of the first switching switch and the second terminal of the second switching switch, the first terminal of the second switching switch is electrically connected to the first terminal of the first capacitor, the second terminal of the first capacitor is electrically connected to the second terminal of the first switching switch and the second terminal of the current ripple eliminator, the single-stage AC/DC PFC circuit and the non-electrolytic capacitor are electrically connected to the first and the second terminals of the current ripple eliminator in parallel, the duty ratio is used to control a turn-on and a turn-off of the first switching switch, and the first switching switch and the second switching switch are complementarily turned on and turned off to each other in the same period, wherein in the same period, when the first switching switch is turned on, the second switching switch is turned off, and when the first switching switch is turned off, the second switching switch is turned on, a minimum cross voltage of the first capacitor is larger than an input voltage of the current ripple eliminator, and a maximum cross voltage of the first capacitor is less than a rated voltage of the first capacitor.
16. A controlling method for an AC/DC converter, comprising:
providing a single-stage AC/DC PFC circuit, a current ripple eliminator electrically connected to the AC/DC PFC circuit in parallel, and a voltage feedback control circuit electrically connected to the current ripple eliminator in parallel;
outputting a control feedback signal from the voltage feedback control circuit to the current ripple eliminator when a peak value of an output voltage of the single-stage AC/DC PFC circuit is not less than a predetermined value such that a first output current caused by the peak value of the output voltage higher than the predetermined value flows into the current ripple eliminator to generate a stored electric energy so as to cause an output voltage of the converter to equal the predetermined value; and
outputting the control feedback signal from the voltage feedback control circuit to the current ripple eliminator when the peak value of the output voltage of the single-stage AC/DC PFC circuit is less than the predetermined value such that the stored electric energy generates a second output current flowing out the current ripple eliminator to cause the output voltage of the converter to equal the predetermined value.
17. The controlling method according to claim 16, wherein the AC/DC converter is the AC/DC converter as claimed in one of claim 5 and claim 7.
18. A controlling method for an AC/DC converter, comprising:
providing a current ripple eliminator having a first inductor and a switching circuit electrically connected to the first inductor in series, wherein the switching circuit has a first capacitor, a first switching switch and a second switching switch, the second switching switch is electrically connected to the first capacitor in series, and the first switching switch is electrically connected to the series-connected second switching switch and the first capacitor in parallel; and
causing a duty ratio of the first switching switch=1−2ω(LB·CB)(1/2), where ω=2πf, f is a working frequency of an AC input voltage of the converter, LB is an inductance of the first inductor, and CB is a capacitance of the first capacitor, and the duty ratio is a fixed value used to minimize a ripple of an output power of the converter.
US14/582,307 2013-12-25 2014-12-24 Electrolytic capacitor-less AC/DC converter and controlling method thereof Expired - Fee Related US9300217B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
TW102148300A TWI530079B (en) 2013-12-25 2013-12-25 Electrolytic capacitor-less ac/dc converter and controlling method thereof
TW102148300 2013-12-25

Publications (2)

Publication Number Publication Date
US20150180325A1 US20150180325A1 (en) 2015-06-25
US9300217B2 true US9300217B2 (en) 2016-03-29

Family

ID=53401192

Family Applications (1)

Application Number Title Priority Date Filing Date
US14/582,307 Expired - Fee Related US9300217B2 (en) 2013-12-25 2014-12-24 Electrolytic capacitor-less AC/DC converter and controlling method thereof

Country Status (2)

Country Link
US (1) US9300217B2 (en)
TW (1) TWI530079B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150266416A1 (en) * 2014-03-21 2015-09-24 Valeo Vision Converter slaved in terms of output current
US9837925B1 (en) 2016-11-01 2017-12-05 Jacobo Aguillón-García Capacitor-less power supply
RU2697049C1 (en) * 2018-07-06 2019-08-09 Федеральное государственное бюджетное образовательное учреждение высшего образования "Томский государственный университет систем управления и радиоэлектроники" (ТУСУР) Control method of alternating voltage to constant voltage converter and device for its implementation
WO2021119793A1 (en) * 2019-12-19 2021-06-24 Embraco Indústria De Compressores E Soluções Em Refrigeração Ltda. Control method and system for single-phase converter and single-phase converter
US20210282244A1 (en) * 2018-07-13 2021-09-09 Ecoglo International Limited Hybrid led / photoluminescent signs

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104869686A (en) * 2014-02-26 2015-08-26 欧司朗有限公司 Driving circuit and illuminating device comprising same
JP6497606B2 (en) * 2014-11-20 2019-04-10 パナソニックＩｐマネジメント株式会社 Lighting device and lighting apparatus using the same
US9614438B2 (en) * 2015-04-29 2017-04-04 Semiconductor Components Industries, Llc Adjusting feedback voltage ripple amplitude to control power supply switching frequency
US9648684B1 (en) 2015-11-24 2017-05-09 King Fahd University Of Petroleum And Minerals Capacitor-less LED drive
GB2544185B (en) * 2016-10-03 2021-03-03 O2Micro Inc Light-source systems and controllers thereof
CN106527648A (en) * 2016-10-25 2017-03-22 郑州云海信息技术有限公司 Power supply device and method of server
CN106787671B (en) * 2016-11-22 2019-09-10 张欣 The circuit of power factor correction for having the function of the no electrolytic capacitor of secondary ripple wave inhibition and fast dynamic response speed
DE102018121246A1 (en) * 2018-08-30 2020-03-05 Brusa Elektronik Ag Adapter device for bidirectional operation
CN111245216B (en) * 2018-11-29 2021-09-03 比亚迪股份有限公司 Correction method and device of PFC circuit and electronic equipment
US10523127B1 (en) * 2019-04-30 2019-12-31 Navitas Semiconductor, Inc. Output clamped flyback converter
US11606849B2 (en) * 2019-06-28 2023-03-14 Texas Instruments Incorporated Active shunt filtering
FR3101493A1 (en) * 2019-10-01 2021-04-02 Airbus Operations (S.A.S.) AC-DC power supply.
US11272597B2 (en) * 2020-08-04 2022-03-08 ERP Power, LLC Digital control of quasi saturated fets for ripple control
CN114340084B (en) * 2021-12-31 2024-04-19 福州大学 Single-stage low-ripple step-down LED driving circuit without electrolytic capacitor and control method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7221111B2 (en) * 2004-12-27 2007-05-22 Kabushiki Kaisha Toshiba Switching power supply device and method of controlling the switching device
US8300438B1 (en) * 2008-11-16 2012-10-30 Edward Herbert Power factor corrected 3-phase Ac-dc power converter using natural modulation
US8344638B2 (en) * 2008-07-29 2013-01-01 Point Somee Limited Liability Company Apparatus, system and method for cascaded power conversion
TWI382637B (en) 2008-07-18 2013-01-11 Spi Electronic Co Ltd The physical circuit as a power correction circuit for the energy storage element
US8477514B2 (en) * 2006-12-01 2013-07-02 Flextronics International Usa, Inc. Power system with power converters having an adaptive controller
US8742674B2 (en) * 2006-01-20 2014-06-03 Point Somee Limited Liability Company Adaptive current regulation for solid state lighting

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7221111B2 (en) * 2004-12-27 2007-05-22 Kabushiki Kaisha Toshiba Switching power supply device and method of controlling the switching device
US8742674B2 (en) * 2006-01-20 2014-06-03 Point Somee Limited Liability Company Adaptive current regulation for solid state lighting
US8477514B2 (en) * 2006-12-01 2013-07-02 Flextronics International Usa, Inc. Power system with power converters having an adaptive controller
TWI382637B (en) 2008-07-18 2013-01-11 Spi Electronic Co Ltd The physical circuit as a power correction circuit for the energy storage element
US8344638B2 (en) * 2008-07-29 2013-01-01 Point Somee Limited Liability Company Apparatus, system and method for cascaded power conversion
US8300438B1 (en) * 2008-11-16 2012-10-30 Edward Herbert Power factor corrected 3-phase Ac-dc power converter using natural modulation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Beibei Wang, et al. "A Method of Reducing the Peak-to-Average Ratio of LED Current for Electrolytic Capacitor-Less AC-DC Drivers", IEEE trans. On Power Electronics, 2010, vol. 25, pp. 592-601.
Kuan-Wen Lee, et al. "A Current Ripple Cancellation Circuit for Electrolytic Capacitor-Less AC-DC LED Driver", Applied Power Electronics Conference and Exposition, 2013, pp. 1058-1061.
Office Action issued in corresponding Taiwanese Patent Application No. 102148300 on May 18, 2015, consisting of 16 pp.
Shu Wang, et al. "A Flicker-Free Electrolytic Capacitor-Less AC-DC LED Driver", IEEE trans. On Power Electronics, 2012, vol. 27, pp. 2318-2325.

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150266416A1 (en) * 2014-03-21 2015-09-24 Valeo Vision Converter slaved in terms of output current
US9837925B1 (en) 2016-11-01 2017-12-05 Jacobo Aguillón-García Capacitor-less power supply
RU2697049C1 (en) * 2018-07-06 2019-08-09 Федеральное государственное бюджетное образовательное учреждение высшего образования "Томский государственный университет систем управления и радиоэлектроники" (ТУСУР) Control method of alternating voltage to constant voltage converter and device for its implementation
US20210282244A1 (en) * 2018-07-13 2021-09-09 Ecoglo International Limited Hybrid led / photoluminescent signs
WO2021119793A1 (en) * 2019-12-19 2021-06-24 Embraco Indústria De Compressores E Soluções Em Refrigeração Ltda. Control method and system for single-phase converter and single-phase converter

Also Published As

Publication number Publication date
TWI530079B (en) 2016-04-11
US20150180325A1 (en) 2015-06-25
TW201526512A (en) 2015-07-01

Similar Documents

Publication Publication Date Title
US9300217B2 (en) Electrolytic capacitor-less AC/DC converter and controlling method thereof
US9997988B2 (en) Zero-crossing detection circuit
US8233292B2 (en) Controllers, systems and methods for controlling power of light sources
US9385616B2 (en) AC/DC power converter
US9258858B2 (en) Active capacitor circuit
US9225241B2 (en) Pulse width modulation DC-DC converter for stabilizing output voltage
US20170027030A1 (en) Led driving circuit
US20160029450A1 (en) High-efficiency led driver and driving method
US10015848B2 (en) Primary side controlled LED driver with ripple cancellation
US20070262760A1 (en) Multiple-output dc-dc converter
US9144125B2 (en) AC-DC power converter
US9078319B2 (en) Conversion control circuit and converter thereof
US8737099B2 (en) Controllers for power converters
US20130308349A1 (en) Switching regulator, the control circuit and the method thereof
US11404959B2 (en) DC/DC power converter
GB2497213A (en) Circuits and methods for driving light sources
GB2503316A (en) Circuits and methods for driving light sources
US11750094B2 (en) Control circuit for a switching converter
CN112383220B (en) Control circuit and switching converter using same
CN112366939A (en) Control circuit and switching converter using same
Pal et al. Improved power quality opto-couplerless Cuk converter for flickerless LED lighting
KR100745305B1 (en) Adaptor using step-down piezoelectric transformer
US10903745B1 (en) Average current mode control architecture
JP6791486B2 (en) Light emitting element drive device and its drive method
KR20150045064A (en) Driving circuit for lighting emitting diode using delay routine and driving method thereof

Legal Events

Date Code Title Description
AS Assignment

Owner name: NATIONAL CHENG KUNG UNIVERSITY, TAIWAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LIANG, TSORNG-JUU;LEE, KUAN-WEN;HSIEH, YI-HSUN;AND OTHERS;SIGNING DATES FROM 20141219 TO 20141223;REEL/FRAME:034583/0487

ZAAA Notice of allowance and fees due

Free format text: ORIGINAL CODE: NOA

ZAAB Notice of allowance mailed

Free format text: ORIGINAL CODE: MN/=.

STCF Information on status: patent grant

Free format text: PATENTED CASE

MAFP Maintenance fee payment

Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YR, SMALL ENTITY (ORIGINAL EVENT CODE: M2551); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

Year of fee payment: 4

FEPP Fee payment procedure

Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

LAPS Lapse for failure to pay maintenance fees

Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20240329